Alkylation with effluent refrigeration and flashed vapor absorption



D. K. BEAVON WIT ALKYLATION H EFFLUENT REFRIGERATION AND FLASHED VAPORABSORPTION Filed Deo. 25, 1955 KIQ @www mum nited States ALKYLATION WITHEFFLUENT REFRIGERATION AND FLASHED VAPOR AESSURPIION David K. Beavon,Los Angeles, Calif., assigner to The Texas Company, New York, N. Y., acorpuration. of Delaware Application December 23, 1955, Serial'No.555,386' s claims. (ci. 2604683.62)

of lower pressure where isobutane is vaporized with con` comitantcooling of the remaining liquid hydrocarbons including alkylate, and theresulting cooled or chilled liquid hydrocarbons are utilized to maintainor assist in maintaining the temperature in the alkylation zone byindirect heat exchange therewith. This patent also discloses that thevaporized isobutane from the flash zone is removed and compressed forrecycling to the alkylation zone.

Elfluent refrigeration possesses certain advantages overauto-refrigeration of the alkylation reaction zone in which lowerboiling hydrocarbons including isobutane are evaporated directly fromthe alkylation reaction zone. In eluent refrigeration, the alkylationzone and settler are maintained under sufficient pressure to preventevaporation of any substantial amount of the lower boiling hydrocarbonsand thereby to insure keeping isobutane and other reactants in liquidphase, whereby the desired high molar excess of liquid isobutane overolefin is maintained throughout the alkylation zone.

Patent No. 2,334,955, Putney, also discloses effluent refrigeration incatalytic isobutane-olen alkylation, and suggests that a portion of thechilled hydrocarbon liquid from the ash zone can be passed in indirectheat exchange with the feed or" reactants to the alkylation zone (pagel, column 2, lines 35-39). This patent teaches the principle in eflluentrefrigeration of dividing the refrigeration load for the alkylation stepbetween elliuent refrigeration supplied to the alkylation zone andeffluent rer'rigeration supplied to pre-chill the feed to thealltylation zone.

Patent No. 2,664,452, Putney, teaches a further improvement in elliuentrefrigeration involving a double flash drum arrangement foraccomplishing this division of the refrigeration load for the alkylationzone. Thus, vaporized propane and isobutane from the rst flash zone,which supplies the chilled hydrocarbon liquid used for refrigeration ofboth the alkylation reaction zone and also the feed to the alkylationzone, is compressed and condensed; recycle and make-up isobutane and thecoridensate are passed to a second llash zone of lower pressure where aportion of the isobutane and lighter hydrocarbon including propane isvaporized With resultant chilling of the remaining liquid isobutane. Theashed hydrocarbons are passed to the alkylate fractionating system fordepropanization and other fractionation. The chilled liquid isobutanefrom the second flash zone is bien recycledvto the alkylation zone. Thesecond flash atet assert Patented Dec. 23, 1958 zone producing chilledliquid isobutane thereby absorbs part of the refrigeration load, andreduces the refrigeration requirements of the irst flash zone in orderto maintain the desired temperature of the alkylation reaction zone.

Preferably strong sulfuric acid of about 88-98% strength is used as acatalyst in alkylation processes employing effluent refrigeration,although other liquid alkylation catalysts which are non-volatile underthe conditions at which isobutane is vaporized in the flash drums foreffluent refrigeration, e. g., aluminum chloride-hydrocarbon complexliquid catalyst, can be employed. These catalysts generate volatile sourdegradation products in reaction mixture under reaction conditions, e.g., SO2 in the case where sulfuric acid is a catalyst, and I-lCl in thethe case where aluminum chloride-hydrocarbon complex liquid is thecatalyst. The very high volatility of these acidic materials permitsthem to escape from flash zones with the volatilized hydrocarbons and tocause corrosion in the apparatus used to recover and separatehydrocarbons ultimately from the flashed material where moistur-e ispresent. Corrosion is particularly bad in the depropanizer fractionatingtower and in vessels receiving wet make-up hydrocarbon streams such asmake-up olen or make-up isobutane.

The present invention relates to an improvement in effluentrefrigeration, for example of the double flash zone type as representedby the Putney Patent 2,664,452. ln accordance with my inventionvaporized isobutane, propane, andl sour degradation products are removedfrom the rst liash zone, then compressed and partially condensed. Vaporsand liquid are separated in a second zone maintained at substantiallycompressor discharge pressure, so that the vapors consist mainly ofpropane and acidic gases while the liquid is isobutane relatively freeof these components. The condensate is passed to another low pressureflash zone wherein additional propane, acidic gaseous degradationproducts, and a portion of isobutane are revaporized with resultantchilling of the remaining condensate. Vapors from said other lowpressure ash zone are commingled with vapors from the lirst flash zone'for compression, while the chilled remaining condensate from said otherllash zone is recycled as feed to the alkylation zone. The vapors fromthe second zone, comprising uncondensed propane, acid gases andisobutane, are absorbed at elevated pressure in the fraction ofhydrocarbon liquid comprising crude alkylation products which iswithdrawn from the first flash zone for subsequent neutralization andfractional distillation into product, by-product, and recycle streams.This fraction of hydrocarbon liquid (herein termed flashed crudealkylate for convenience) and the absorbed vapors are both neutralized,and the resultant neutralized mixture of hydrocarbon liquid and absorbedvapors are then fractionally distilled to obtain product alkylate, torid the system of low boilers such as propane, and to recover unreactedexcess isobutane for recycle to the alkylation zone'.

The absorption step in my process can be conducted with theun-neutralized' flashed crude alk'ylate prior to or during itslneutralization or after this crude hydrocarbon mixture has beenneutralized and still remains admixed with neutralizing solution, e. g.,aqueous caustic soda, soda ash-or the like. The caustic treated mixtureis then water washed and'passed to a fractionating system.

My process is based on the realization that the dashed crude alkylateliquid leaving the lrst flash zone of lower pressure has considerableabsorption capacity for propane andl isobutane at a pressure above about30 p, s. i. g.; broadly at pressure between about 40 andy about 100 p.s. g., and typically at 52455 p. s. i. g. By this absorption,y lowboiling' vaporized components such as prol* pane, ethane, and lightermaterials and sour volatile substances are removed from the alkylationsystem quite readily; the subsequent neutralization of the acidicvolatile degradation products contaminating these vaporized componentsprotects the expensive fractionating equipment in the subsequentprocessing steps without necessitating extra neutralization apparatus.

The invention is illustrated in the attached drawings wherein Fig. 1represents a flow diagram of a typical alkylation plant employing analkylation reactor of the internal recirculated type, e. g., a so-calledStratco- Contactor, although my invention can be also applied to otherconventional types of alkylation reactor systems such as the pump andtime tank type. In this embodiment, absorption of vapors is done in avessel pro-vided for this purpose. Fig. 2 shows a modification of myinvention wherein the vapors vented from the second flash zone arecontacted for absorption and neutralization with neutralized flash crudealkylate as it is still in contact with a caustic solution.

Referring to the drawing, the olefin feed stream is introduced by line18 and make-up isobutane is added thereto by line 11. It will beunderstood that the olefin feed stream is generally a C4 cracked gasfraction containing butanes and butylenes and termed BB feed, preferablyone which contains less than about 30 liquid volume percent of normalbutane. However, a mixed (S3-C4 olefin feed stream can be employed, orother normally gaseous and normally liquid oleiins can be used. Theresulting feed stream, mixed with recycled recovered isobutane from line12, is passed through feed exchanger 13 which is chilled by effluentrefrigeration as described hereinafter. It is then introduced by line 14into water separator 15, where, as a result of chilling and standing, awater layer is decanted and withdrawn thro-ugh line 16. The feedcontaining recycled isobutane is then passed through line 17 into header18, together with a chilled liquid recycle fraction from the third flashdrum, hereinafter described, entering header 18 from line 46.

Line 18 discharges into contactor 19. The liquid acid: hydrocarbonvolume ratio in the contactor 19 is maintained about 1:1 and a contacttime in the contactor is about to l5 minutes in the conventional manner.Where sulfuric acid is utilized as catalyst, make-up 98% H2804 is addedto the system through line 24 to keep the acid strength in the contactorat about 8892% strength. Mol ratio of isobutane to olefin supplied tothe contactor (including isobutane recycle) is substantially in excessof 1:1 and generally is about 4:1 to 10:1. The eiuenthydrocarbon-catalyst mixture is withdrawn from the contactor throughline 20 and passed through settler 21 where the heavier catalyst phaseis separated from the hydrocarbon phase. The catalyst phase is recycledto contactor 19 through line 22, with catalyst purge being withdrawnthrough line 23 and make-up catalyst being added through line 24 tomaintain desired acid strength in the contacting system.

The lighter hydrocarbon phase is withdrawn from the top of settler 21through line 2S and passed into first flash drum 26. Here the pressureis dropped from about 25-40 p. s. i. a. existing in the alkylation andcatalyst settling system to approximately atmospheric pressure or belowby connecting the suction side of compressor 39 through vapor line 34 tothe upper portion of first flash drum 26. This results in isobutane andlighter hydrocarbons including propane being vaporized in' the lirstiiash drum with resulting chilling of the remaining unvaporizedhydrocarbon liquid to about F. or lower. A portion of the so-chilledhydrocarbon liquid s withdrawn from tiash drum 26 by line 3l), pump 31,line 32 to feed exchanger 13 to pre-chill the feed to the alkylationzone. This portion of the hydrocarbon liquid (the flashed crudealkylate) is then passed by line 33 to absorber 48. Another portion ofthe chilled hydrocarbon liquid .from flash drum 26 is passed by line 27to the chilling coils in the alkylation contactor, the distributing headof said chilling coils being represented symbolically in the drawing byitem 28. ln the arrangement sho-wn ash drum 26 is elevated above thechilling coil so that gravity flow is utilized to convey the chilledhydrocarbon liquid through line 27 to the chilling coils. In the coils aportion of the isobutane and lighter hydrocarbons is vaporized toprovide refrigeration with an incidental thermosyphon eliect whichreturns mixed liquid and vapor through line 29 into the iiash'drum 26.However, it will be understood that a pump can be provided for positivecirculation through the cooling coils in contactor 19.

Vaporized isobutane, propane, and sour degradation products removed fromliash drum 26 by vapor line 34 pass into compressor trap 35, wherein anyheavier er1'- trained liquid drops out and can be removed by pump 36 andline 37. The vapors then pass by vapor line 38 to compressor 39 whichraises the pressure thereof to about 52-55 p. s. i. g., and forces themby vapor line 40 through water cooled condenser 41 and line 42 intosecond ash drum 43. Drum 43 is, in this case, primarily a disengagingchamber, but is called a tiash drum herein for convenience. Uncondensedvapors from the second flash drum are withdrawn through line 47.

The condensate from second tiash drum 43 is released 'by pressureregulating valve 143 thru line 44 into third flash drum 103 (which isoperated at approximately atmospheric pressure) whereby additionalpropane, volatile sour degradation products, and a portion' of isobutaneare revaporized with the resultant chilling of the remaining condensate.The vapo-rs from third flash drum 103 ow through line 145 to compressortrap 35, joining vapors from first flash drum 26 passing thereto.Chilled condensate, preponderantly isobutane, is withdrawn from thirdash drum 103 by lin'e 144 and pump 4S, then passed through line 46 intoheader 18 for recycle into contacto-r 19. Thus the isobutane recyclefrom the third iiash drum is utilized to further chill the feed to thealkylation zone by mixing therewith, thereby distributing therefrigeration load between the first and third flash drums.

The uncondensed vapors from the second ash drum are passed by line 47into absorber 48 wherein they are contacted with liashed crude alkylatefrom line 33 after it has been used to chill the feed exchanger 13. Theabsorber pressure is essentially the same as that in the second liashdrum. The mixture of flashed crude alkylate enriched by absorbed vaporsfrom the second flash drum comprising propane, isobutane, and sourdegradation products, is withdrawn from the absorber by line 49, pump 50and line 51 for feeding into conventional caustic mixer 52. If desired,a portion of the flashed crude alkylate can be diverted from absorber 48to the caustic washer by means of bypass 33a.

In caustic washer 52 the enriched iiashed crude alkylate is thoroughlymixed and neutralized with a recycle iiow of aqueous 5% by weight ofcaustic soda. The mixer eftiuent is passed through line 54 into settlingtank 55 wherein it is separated into an upper hydrocarbon phase and alower aqueous phase. The aqueous phase is withdrawn from settling tank55 by line 56 and recirculated into line 53 by pump 59. Spent causticsolution can be withdrawn from line 57 and make-up caustic solutionadded through line 58.

r)The neutralized hydrocarbon phase is Withdrawn from settling tank 55through line 60, mixed with water (entering line 61) in mixer 62, andthis mixture conducted through line 63 into settling tank 64 wherein alower water phase and an upper hydrocarbon phase are formed. The waterphase is withdrawn from settling tank 64 by line 65.

The upper hydrocarbon phase is passed through line 66 into depropanizertower 67. This tower is operated to make a sharp separation betweenpropane'and lighter hydrocarbons, removed by overhead vapor line 68, and

C4 and heavier hydrocarbons, removed as a bottoms fraction through line75. Propane vapors from tower 67 are condensed in condenser 69 and aredischarged through line i into accumulator 71. A portion of thecondensate in accummulator 71 is pumped back to the depropanizer asredux, and the remainder is discharged from the system by means of line72.

The depropanizer bottoms are passed by line 75 into deisobutanizer tower76. This tower is operated to make sharp separation between isohutaneand normal butane and heavier to thereby remove overhead, by vapor line7S, an essentially isobutane vapor which passes through condenser i9into accummulator 80. A portion of the isobutane condensate is pumpedthrough line 81 as retlux to the deisobutanizer. The remainder of theisobutane condensate is passed through line 12, optionally through awater pre-cooler, and then mixed with the olefin and isobutane feeds inadvance of feed exchanger 13.

The liquid product from deisobutanizer 76 passes by line 82 to productdebutanizer 84 where normal butane is removed overhead by vapor line 86through condenser 87 to accumulator 88. A portion of the liquid normalbutane is reuxed by pump to debutanizer 76 through line 89, and thebalance is discharged by line 90 to tankage for feed to an isomerizationunit, or as blending stock, or for other purposes.

The debutanizer bottoms fraction passes by line 91 to fractionator 93wherein the desired aviation alkylate or high octane motor gasolinealkylate fraction is removed overhead through line 95 and condenser 96into accumulator 97. A portion of the condensate is returned as refluxto the fractionator by line 98, and the remainder discharged to tankageby line 99. The heavier alkylate bottoms are withdrawn through line 100,cooler 1101, and line 102 to tankage to serve as cracking stock or forother uses.

in the foregoing drawing only the principal pumps have -been shown andfractionating tower reboilers are `indicated symbolically at the bottomsof the towers. Ad-

ditional pumps and various auxiliary equipment can be supplied inconventional manner where necessary or desirable, and the order of flowthrough the various fractionating towers can be changed as is necessaryor desirable without departing from the principles of this invention.

Fig. 2 shows a modilication of the scheme hereinbefore described. Thenumerals in Fig. 2 correspond to the equipment items enumerated inFig. 1. in this special case wherein flash drum 43 is operated at aconsiderably higher pressure, e. g., to 15 p. s. i., than the causticsettling tank 55, vapors from dash drum 43 can be contacted directly forabsorption in the neutralized flash crude alkylate emerging from mixer52 with the caustic soda solution. Neutralization of the vapors andabsorption of the hydrocarbon vapor take place essentiallysimultaneously and eliminate a separate absorbing vessel and pump. 1fdesired a booster compressor and necessary auxiliary equipment can beinstalled to take suction out of the flash drum 43 forpassing it intothe discharge of mixer 52, or into lines 33 or 53 feeding the mixer. Thelatter modification permits the operation of flash drum 43 at somewhatlower pressure than either of the schemes outlined in Figures 1 or 2.

The following is given as an example of the present invention, and itrepresents the operation of a 1750 barrel per day aviation alkylateplant according to scheme shown in Fig. 1. An olefin feed stock isintroduced through line 10 at a charge rate of 80 bbl./hr. with acomposition in liquid volume percent of 6.6% propane and lighter, 19.0%isobutane, 51.0% butylenes, 20.4% normal butane, and 3.0% C5s. Make-upisobutane from line 11 is introduced at the rate of 38 bbls./hr. with acomposition in liquid volume percent of 10% propane, 87% isobutane, and3% normal butane. This is mixed with.recycledisobutane from line `12introduced-at the rate of 77 bbL/hr. -with a composition'in liquidvolume percent 10% of-C3, ,-87% isobutane, and-.3% normal butane. Theforegoing mixedfeed, at a temperature of approximately `"-F.,fpassesthrough exchanger 13 and is chilled to 60 F. by hydrocarbon effluentfrom dash drum 26 having a temperature of 30 F. at the entry toexchanger 13 anda temperature of 80 F. at the exit thereof. vTheresultant chilled vfeed-is then mixed with chilled recycled isobutanefrom flash drum 43, supplied at a temperature of 13 -F. and at feed rateof 156 bbl./-hr.,with arcomposition in liquid volume percent of 9.7% C3,73.6% isobutane, 15.7% normal butane and 1% .C5 and heavier. The totalreactor hydrocarbon charge of 351 bbl/hr., with l,a composition inliquid volume percent of 9%.C3, 66% isobutane, 12% butylenes, 12.5%normal butane,.and 0.5% C5 and heavier, is supplied to the alkylationcontacter at a temperature of about 40 F.; 1 bbl./hr. of make-up of 98%i-H2SO4 is supplied together vwith 229 bbl/hr. of recycle H2SO4 tothealkylation reaction zone, thereby giving a hydrocarbon to acid volumeratio in the -contactor of 1:1 with a maintained system acidity of about92% HZSOp Hydrocarbon efuent, removed from settler`21 by line f25 to`flash drum `26 at the rate of 333 bbL/hr., has composition in liquidvolume percent of 9% C3, 55% yisobutane, 13% normal butane, 1% C5, and22% alkylate. In flash drum 26 the pressure is dropped to 15 p. s. i. a.with resulting dashing of l206 bbL/hr. of vapo-rs having approximatecomposition in liquid volume percent of 17% C3, 69% isobutane,13% normalbutane, and 1% C5 and heavier. 126 bbl/hr. of chilled hydrocarbon liquidfor refrigeration is thus provided having a composition in liquid volumeApercent of 27% -isobutane, 13% normal butane, 1% C5,and about 58%alkylate. This chilled hydrocarbon liquid passes through feed exchanger13 where its temperature is'raised to 80 F then flows thro-ugh line 33to absorber 48.

The vapors from line 38 are compressed, partially condensed, andadmitted to-flashdrum 43. Herein some additional dashing takes placeatfpressure of 69p. s. i. a.

`anda temperature about 80 F., resulting in separation of 51 bbL/hr. ofvapors having-approximate composition inliquid volume percent of 30% C3,64% isobutane, 6% normalbutane together with volatile acidic degradationproducts.

LiquidV condensate from flash drum 43 (-215 bbl./hr. containingapproximately 19% propane, 66% iso-butane, 14% butane, and 1%y C5) iiowsthrough line 44 and thro-ttle valve 143 into third flash drum 103, whichis maintained at essentially 15 p. s. i. a.; pressure. The flashingliquid auto-refrigerates to a temperature about 13 F. Vapors areproduced (59 bbl./hr. containing approximately in liquid volume percent45% propane, 47% isobutane, and 8% butane). These vapors iiow throughline 145 into compressor trap 35, joining vapors from first ilash drum26.

From drum 103, 156 bbl/hr. of chilled hydrocarbon liquid refrigerant arethus provided having a composition in liquid volume percent of 9.7% C3,73.6% isobutane, 15.7% normal butane, 1% C5. This is passed through line144, pump 45, and line 46 into header 18 for recycle to the contactor.

The vapors from second ash drum 43 are absorbed in flashed crudealkylate from line 33 at pressure at about 65 p. s. i. a. Theso-enriched crude alkylate is neutralized with caustic soda solution inmixer 52, decanted in settling tank 55, water washed in mixer 63, andredecanted in settling tank 64 for transmission to depropanizer 67.

Feed to the depropanizer amounts to 177 bbL/hr. having composition inliquid volume percent of 8.5% C3, 38% isobutane, 11% normal butane, 1%C5, and about 41% alkylate. The depropanizer overhead is removed throughline 72 at the rate of 15 rbbL/hr. This provides a depropanized bottomsat the rate of 161 bbl./hr. which is passed to deisobutanizer 76.

An'overhead from the isobutanizer is passed through line 12 as recycledisobutane at the rate and in the composition hereinbefore described formixing with charge olefin and make-up isobutane. The bottoms from thedeisobutanizer are fractionally distilled in product debutanizer 84 toobtain butane as an overhead product. The alkylate bottoms from productdebutanizer 84 are fractionaily distilled in fractionator 93 to producean Overhead product of about 66 bbl./hr. aviation alkylate, which iswithdrawn through line 99, and 7 bbl./hr. of heavy alkylate, which iswithdrawn through line 102.

Obviously, many modifications and variations of the invention ashereinbefore set forth may be made without departing from the spirit andscope thereof, and therefore only such limitations should be imposed asare indicated in the appended claims.

I claim:

1. In a process for catalytic isobutane-oleiin alkylation employingeiiuent refrigeration, wherein isobutane in molar excess and olenic feedstock containing some propane are contacted in liquid phase in analkylation zone with a liquid catalyst under alkylating conditions, saidcatalyst being capable of generating volatile acidic degradationproducts in the reaction mixture under reaction conditicns, theresulting reaction mixture is separated into a liquid hydrocarbon phaseand a liquid catalyst phase, separated liquid hydrocarbon phase ispassed to a ash zone of lower pressure to evaporate isobutane, volatileacidic degradation products, and propane therefrom and concomitantlychill the remaining hydrocarbon liquid comprising the crude alkylationproduct, at least a portion of the chilled hydrocarbon liquid isemployed as a heat exchange medium to assist in controlling temperaturein said alkylation zone, and the remainder of said chilled hydrocarbonliquid comprising the crude alkylaticn products is withdrawn from saidtiash zone of lowerl pressure for subsequent neutralization andfractional distillation, the improvement which comprises: removing astream of evaporated isobutane, propane, and volatile acidic degradationproducts from said flash zone of lower pressure; compressing said streamand con- -densing liquid isobutane therefrom; separating the resultingsour vapor phase from the condensed liquid isobutane-containing phase;absorbing the resulting sour vapor phase at elevated pressure betweenabout 30 and 100 p. s. i. g. in said remainder of hydrocarbon liquidcomprising crude alkylation products; and neutralizing both saidremainder of hydrocarbon liquid and the vapors absorbed therein.

2. The process of claim 1 wherein said liquid catalyst is sulfuric acid,and the absorption step is conducted prior 8 to neutralization of saidremainder of hydrocarbon liquid comprising crude alkylation products.

3. The process of claim l wherein said liquid catalyst is sulfuric acid,and the absorption step is conducted concurrent with neutralization ofsaid remainder of hydrocarbon liquid comprising crude allcylationproducts.

4. In a process for catalytic iso-butane-olefin alkylation employingefliuent refrigeration, wherein isobutane in molar excess and olenicfeed stock containing some propane are contacted in liquid phase in analliylation zone with a liquid catalyst under alkylating conditions,said catalyst being capable of generating volatile acidic degradationpro-ducts in the reaction mixture under reaction conditions, theresulting reaction mixture is separated into a liquid hydrocarbon phaseand a liquid catalyst phase, separated liquid hydrocarbon phase ispassed to a flash zone of lower pressure to evaporate isobutane,volatile acidic degradation products, and propane therefrom andconcomitantly to chill the remaining hydrocarbon liquid comprising thecrude alkylation product, at least a portion of the chilled hydrocarbonliquid is employed as a heat exchange medium to assist in controllingtemperature in said alkylation zone, and the remainder of said chilledhydrocarbon liquid comprising the crude alkylation products is withdrawnfrom said dash zone of lower pressure for subsequent neutralization andfractional distillation, the improvement which comprises removing astream of evaporated isobutane, propane and volatile acidic degradationproducts from said dash zone of lower pressure. condensing isobutanefrom said stream and separating the resulting remaining sour vapor phasefrom the condensed liquid isobutane phase, absorbing said separated sourvapor phase in said remainder o-f hydrocarbon liquid comprising crudealkylation products at elevated pressure between about 30 to 100 p. s.i. g., and neutralizing both said remainder of hydrocarbon liquid andthe vapors absorbed therein.

5. The process of claim 1 wherein the separated condensed liquidisobutane phase is reashed in a subsequent dash zone of lower pressure,the resulting vapors and residual chilled isobutane are separated, saidlast-mentioned resulting vapors are combined with said stream ofevaporated isobutane, propane and volatile acidic degradation products,and said last-mentioned residual chilled liquid isobutane is returned tosaid alkylation zone.

References Cited in the tile of this patent UNITED STATES PATENTS2,342,364 Parker Feb. 22, 1944 2,370,771 Bowerman Mar. 6, 1945 2,374,262Anderson Apr. 24, 1945 2,664,452 Putney Dec. 29, 1953

1. IN A PROCESS FOR CATALYTIC ISOBUTANE-OLEFIN ALKYLATION EMPLOYINGEFFLUENT REFRIGERATION, WHEREIN ISOBUTANE IN MOLAR EXCESS AND OLEFINICFEED STOCK CONTAINING SOME PROPANE ARE CONTACTED IN LIQUID PHSE IN ANALKYLATION